From the viewpoint of reducing the burden on the environment, such as reducing emission of carbon dioxide (CO2) and consumption of fuel, it is desired to improve energy efficiency of vehicles. Accordingly, for example, in vehicle headlight devices (referred to below as headlights) or the like, downsizing, weight reduction, and power efficiency improvement are required. “Headlight” refers to an illuminating device that is mounted on a transportation machine or the like and used to improve visibility for an operator and conspicuity to the outside. A vehicle headlight is also referred to as a headlamp or headlight.
Thus, when a headlight is taken as an example, it is desired to employ, as a light source, a semiconductor light source having higher luminous efficiency than conventional halogen bulbs (lamp light sources). “Semiconductor light source” refers to, for example, a light emitting diode (LED), laser diode (LD), or the like.
Headlights satisfy a predetermined light distribution pattern specified by road traffic rules or the like. Thus, their optical parts, such as lenses, are arranged accurately.
When an optical part is mounted to a holder for holding a part or the like so that it can withstand vibration of the vehicle, deformation of the part due to heat or the like may damage the optical part. An example is the case where it is mounted using a ring-shaped lens holder. In particular, when an optical part is fixed to a lens barrel, the optical part is highly likely to be damaged. A “lens barrel” is a cylindrical part for supporting lens or the like and performing blocking of outside light or other functions, in a camera or the like.
As an optical part mounting structure that can handle such vibration or heat with a small structure, a method using a plate spring is known.
Patent Literature 1 discloses plate springs 6 that urge a second lens frame 4. The plate springs 6 are arranged at predetermined pitches in a circumferential direction; a base end of each plate spring 6 is detachably fixed to a chucking base 5 with a set screw 7, and the other end is a free end and floated in the optical axis direction.